While Google’s MVNO service is perfect for subscribers that only use a little bit of data every month, it’s not particularly suited for heavy data users. However, today, Project Fi is trying to reach out to more customers with “Bill Protection” — its own take on an unlimited plan.

Project Fi charges $20 for unlimited texting and calling in the U.S., with data costing $10 per GB. With the new Bill Protection, subscribers can effectively pay an $80 monthly bill for “unlimited” data that gets throttled to “slower data speeds” after 15GB.

Bill Protection gives you the peace of mind to use extra data when you need it. In months when you use more than 6 GB of data, we’ll cap your charges for calls & texts plus data at $80, and allow you to continue using high speed data for free—similar to an unlimited plan.

“Super heavy data users” or those who go over 15GB make up less than 1% of current Fi users today, according to Google. This slow down would be in line with the practices of most U.S. cellular carriers. Meanwhile, Bill Protection kicks in at different usage levels for those in group plans:

2 people: 10GB

3 people: 12GB

4 people: 14GB

5 people: 16GB

6 people: 18GB

Those who want to avoid the throttled speeds can pay $10/GB for data usage above 15GB. The best part of Bill Protection is that it follows Fi’s other aspects: you are still only paying for the data you use.

And here’s the kicker: with Bill Protection you’ll never have to pay for unlimited data in months when you don’t actually need it. If you only use 1.4 GB of data, at the end of the month you’ll pay just $34 instead of $80.

Meanwhile, Bill Protection also applies to data used through data-only SIM cards. The service is rolling out today for new subscribers and will be applied for existing ones on the next billing cycle.